[Python-ideas] allow `lambda' to be spelled λ

Chris Angelico rosuav at gmail.com
Wed Jul 13 01:49:13 EDT 2016

On Wed, Jul 13, 2016 at 3:43 PM, Pavol Lisy <pavol.lisy at gmail.com> wrote:
> 3.
> Questions around "only one possibilities how to write it" could be
> probably answered with this?
>   a<b
>   a.__lt__(b)

Those aren't the same, though. One is the interface, the other is the
implementation. Dunder methods are for defining, not for calling.

rosuav at sikorsky:~$ python3
Python 3.6.0a2+ (default:4ef2404d343e, Jul 11 2016, 12:37:20)
[GCC 5.3.1 20160528] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> class B:
...     def __gt__(self, other):
...         print("Am I greater than %s?" % other)
...         return False
>>> a = 5
>>> b = B()
>>> a < b
Am I greater than 5?

Operators can have multiple implementations (in this case, the
interpreter found that "int < B" didn't have an implementation, so it
switched it to b > a and re-evaluated).


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